Apparatus for forming molds



Dec. 14 1926. 1,610,472

J. A. RATHBONE APPARATUS FOR FORMING MOLDS Filed April 28 1924 2 Sheets-Sheet 1 & f uveutoz 2 Sheets-Sheet 2 Dec. 14,1926. I J. A. RATHBONE APPARATUS FOR FORMING MOLDS Filed April 28, 1924 M x .h L i 1:21P.

Patented 14, 1926.

JOHN A. RA'IJHBQNIE, 013 DETROIT, MICHIGAN.

aren't FFICE.

APPARATUS FOR FORMING MOLDS.

Application filed April 28, 1924-. Serial No. 709,637.

The invention relates to the art of forming sand molds and more particularly to the forming of such molds by the use of molding machines; The process which is carried out by such machines comprises essentially: first, filling a mold flask and cooperating sand frame with loose sand and then impressing the print of the pattern in the sand and compressing the same to the required density by the operation of a ram. Where multiple or stack molds are being formed, opposed registering patterns are secured respectively to the stationary head and movable ramming head and the sand which is in the flask is compressed between these heads, usually with a relatively high pressure. It has been found in practice that molds so formed, when released from the machine, sometimes alter in shape, particularly by the bulging outward of the center portion of the sand body. This defect has been traced to the lateral pressure of the sand against the walls of the flask and the lack of rigidity in such walls.

Thus

when the compression of the sand is accomplished in a short interval, the sides of the flask will be sprung outward, and upon the release of the ram, the resilient pressure of these sides reacting upon the sand will bulge the same as before described.

It is the object of the present invention to overcome this defect, which may be accomplished in various specific ways. One method of accomplishment is to impart to the pattern by springing the same or otherwise, a slightly convex form, which will produce initially a corresponding concave in the sand. This will permit the flask to expand and upon contracting the bulging of the center will' only compensate for its original concavity. Another method of correction is to impart suflicient rigidity to the flask to resist eXpan sion. This could be accomplished by a permanent reinforcement of the sidewalls of the flask,'but such construction would both increase the weight and the cost of manufacture.

A third method of correction is to hereinafter.

In the drawings:

Figure 1 is a sectional elevation of the machine Figure 2 is a transverse section thereof;

Figure 3 is a similar View showing a modified construction;

' Figure a is a View similar to a portion of Fig. 1 showing'the parts in a different position of adjustment.

As shown, A is the stationary ramming head which is mounted on the cross head 13 of the molding machine. C is the movable ramming head, which is forced upward by the operation of a piston D. E is the flasksupporting frame on the head C, F the flask supported thereon, and G the superposed sand frame. The opposed drag and cope patterns H and T are respectively mounted on the stationary and movable heads.

The flask frame and flask are held in proper alignment by pins J secured to and extending upward from the head C, these being usually arranged at the cent-er of op posite ends of the flask. lVith my improvement I provide, in addition. to these pins J, similar pins K arranged centrally at opposite sides of the flask and also preferably passing upward through the flask frame. The flask F is provided with outwardly projecting lugs L for hearing against the projecting ends of the pins K, so that any lateral thrust on the flask will be carried into the pins K, the flask frame and the head C. This will prevent any expansion of the flask under the internal pressure of the compressed sand and will avoid the difliculty above referred to.

For drawing the lower pattern from the mold the machine is provided with the usual stool plate M and the cooperating abutments N. These operate during the descent of the ram to arrest or retard movement of the stool plate, flask frame and flask, while the ram and pattern plate continue to move. This same action will withdraw the flask from its bearing against the pin K so as to permit of easily lifting off the mold from the machine.

A modified construction for accomplishing the same purpose is shown in Figure 3 in which the stationary ram A. is provided with depending members 0 on opposite sides thereof, which engage the bearings L on the flask in the same manner as such bearings are engaged by the pin K in the construction just described. It is obvious that various other constructions may be used for the same purpose, but in all the internal pressure of the sand upon the flask during the ramming action is transmitted to a reinforcing member, which Will hold the flask from expansion.

As the general operation of molding machines of this type is well understood, it is unnecessary to further describe the same.

What I claim as my invention is:

1. In a molding machine, the combination with a stationary frame, a reciprocatory rain, a pattern plate and a flask, of means for positioning said flask with respect to said frame and ram, and means independent of said positioning means operative during the compression of the sand in the flask by the action of said am for holding said flask from lateral expansion.

2. In a molding machine, the combination With a stationary frame, a reciprocatory ram, a pattern and a flask, of means on said frame for embracing opposite sides of the flask during the compression of the sand therein by the ram, said means serving to hold said flask from lateral expansion.

In a molding machine, the combination With a stationary frame, a reciprocatory ram, a pattern plate and a flask, of elements for reinforcing the flask during ramming of a mold within said flask, said elements being mounted upon the machine independently of said flask, and being engageabie with opposite side Walls of the flask through travel of the rain to its mold engaging position.

i. In molding machine, the combination with a stationary frame, a reciprocatory ram, a pattern plate and a, flask, of means engaging two opposite Walls of said flask for positioning the flask for use in the machine, and means engageable with two other Walls of the flask for reinforcing said Walls during the ramming operation.

in testimony whereof I affix my signature.

JOHN A. RATHBONE. 

